In this study, the effects of reinforcement volume fraction, matrix and reinforcement particle sizes and their interactions on the flexural strength of Al-SiCp metal matrix composites manufactured by powder metallurgy method were investigated by using central composite design (CCD). An experimental plan for CCD with three factors and five levels was used to optimize the required number of experiments. The fabricated composites were reinforced with SiC particles of 2.39, 7.5, 15, 22.5 and 27.61 volume fractions. The particle sizes of 45, 62, 87, 112, and 129 mu m were determined for both matrix and reinforcement particles. Experimental and numerical results show that the main effects of factors and their interactions are significant on the flexural strength. Among all factors, the main effect of volume fraction dominates the main effect of other two factors. Interaction between matrix particle size and reinforcement particle size is much more important at low volume fraction compared to that at high volume fraction. The high flexural strength values at low volume fractions are obtained when matrix particle size is equal to or smaller than reinforcement particle size while those at high volume fraction can be only reached when matrix particle size is much smaller than that of reinforcement particle. (C) 2012 Elsevier B.V. All rights reserved.